In many older driving devices for driving elongate display members of the above type, it has been necessary to carry out the driving with a motor which is programmed to stop each time the display members are standing still in their display positions. At e.g. trilateral, elongate display members, it has therefore been necessary to stop the motor three times during each revolution for displaying all three sides. Since signs for consecutive, repeated display or presentation of series of images are in continuous operation day and night throughout the year, the driving motor must be capable of performing an enormous number of starts and stops, thereby making heavy demands upon the motor and the control device therefor. This means, inter alia, that either expensive motor units must be used or frequent shutdowns must be allowed for.
Where the driving devices are constructed such that the motor can rotate continuously without stopping and starting, it has up to now been possible to eliminate in a satisfactory manner, the risk that the display members are dislodged in an impermissible manner during rotation or when standing still in their display positions. The display members can be brought "out of phase" by gusts of wind, heavy rain or other outer circumstances and shutdowns of the driving device can thereby occur.
It has until recently neither been possible, in driving devices which permit rotation of the elongate display members in one direction as well as the opposite direction, to at least substantially eliminate the risk for that said display members are rotated in an impermissible manner when they are standing still in their display positions.
However, by means of the driving device of SE, B, 466 576 it is ensured that one can use a driving motor which during the entire time of display rotates the drive shaft of the driving device continuously in one direction of rotation, i.e. completely without constantly starting and stopping the motor. It is also ensured that the display members can be blocked against rotation and not dislodged when standing still in their display positions. It will also be possible to operate the driving motor in the opposite direction if one wishes to rotate the display members in this opposite direction and the display members are even now prevented from being dislodged when they stand still.